I have crack. In my turbo. Exhaust side, in the scroll, behind the bolt-on piece that holds the internal wastegate. Decent size, maybe an inch on one side and another one slightly shorter about 180* opposite across the exhaust hole.

Could this cause a surging / temporary boost cut under boost? Feels like a gorilla is alternately pushing/pulling the car, but this happens only when it's warmed up.

I have been thinking that it's the OD clutch sliping in the M46, but I don't want to replace the trans if I don't have to.

Oh, '85 244 B21FTi.

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'91 745 with 15g and MBC

Quote:

Originally Posted by Quin

that's called a crutch. like a roll cage for a joint.

Quote:

Originally Posted by casioqv

Tbricks... where half the members need to spends months essentially sourcing and building entire cars from miscellaneous used parts before they can drive a few hours and drink some beer with their friends.

These housings do commonly crack around the wastegate hole area. I would think that if the crack is leaking enough it would reduce the boost you generate not cause surging. That sounds like something else like fuel issues from weak intank pump, air leaks under boost or some other problem. How high is the boost set? You may just be hitting the fuel cut of the overboost switch if you have a mbc set to high or it's spiking.

The crack isn't on the wastegate piece - it's on the snailshell part where the wastegate piece bolts on

Quote:

Originally Posted by dl242gt

I would think that if the crack is leaking enough it would reduce the boost you generate not cause surging.

That's what I thought too - just wanted to make sure.

Quote:

Originally Posted by dl242gt

That sounds like something else like fuel issues from weak intank pump, air leaks under boost or some other problem. How high is the boost set? You may just be hitting the fuel cut of the overboost switch if you have a mbc set to high or it's spiking.

Could be intank pump- I'll check that this weekend.

Boost is set to 12-13 PSI (barely above stock, I know) I disconnected the overboost switch and it still had the same problem, so I reconnected it. I also know I'm not collapsing my intake hose since it is now almost covered in hose clamps.

I pulled mine off and I have the same cracks, they are over an inch long and all the way through, i'll let you know how it feels after I put the new one on. I just have to reclock it and its ready to go